igrep not support utf-8

[erachenko23]

1. Create in zoo entry with utf-8 text (russian language for example)

check via zk-web - OK

2. get value by zk-shell
   zk-shell --run-once "get /test/tester" 10.12.47.107:2181
   тестовая строка

zk-shell return correct value - OK

3. igrep value
   zk-shell --run-once "igrep / 'тестовая строка' true" 10.12.47.107:2181

NOK - return empty result

[rgs1]

cc: @Yasumoto